Effect of Attention Variation in Stroke Patients: Analysis of Single Trial Movement-Related Cortical Potentials

We have previously developed a Brain-computer interface (BCI) for neuromodulation based on movement related cortical potentials (MRCP). Since successful induction of plasticity is dependent on the attention of the user, the aim of this study was to analyze the changes in MRCPs during imposed attentional shifts in patients. We recorded EEG signals from Cz and its surrounding channels in seven chronic stroke patients, who were asked to attempt ankle dorsiflexion in two subsets of 30 repetitions. Each subset was separated from the other by an auditory oddball task comprised of three tones. Patients were asked to detect the target tone by pressing a button. Nine temporal features were extracted from single trial MRCPs and compared between the two subsets of dorsiflexion that were interspersed by the oddball task. The amplitude of the MRCP negativity, pre-movement slopes, pre-movement variability and movement detection latency and accuracy changed significantly when attention was diverted from the main task of dorsiflexion. This has significant implications for BCIs designed to induce plasticity since detection failure will result in inappropriate device control.